Virinchi means BrahmA. prabHRtayaH: and the others of the kind. They tried to describe Your beauty ‘tvadIyam soundaryam’. The word ‘tulA’ stands for a pair of weighing scales. In one pan of the scales we put the object to be weighed and in the other pan we place the ‘weight’ whose weight we know. In other words when we don’t know the weight of something we calculate it by comparing it with something whose weight we know.
So when you don’t know how to describe the beauty of ambaal, what we do is to look for something whose beauty we know. Such a ‘weight’ we know is known by the name of ‘analogy’ or ‘example’. The face is like the moon, the eyes are like lotuses, the hair on the head is like a beehive - all these are examples and analogies, which help us to comprehend the ‘weight’ of the beauty of ambaal, in terms of known ‘weights’.